One method for scanning luggage for illegal materials, such as explosives and drugs, is collecting vapors and small particles (referred to collectively herein as vapors) from the luggage and passing the vapors to a detection system (also known as a trace analyzer) which determines whether the vapors include traces of specific materials.
One type of collection apparatus includes hand held machines, such as described in U.S. Pat. No. 4,909,090 to McGown et al., U.S. Pat. No. 5,092,220 to Rounbehler, and U.S. Pat. No. 5,123,274 to Carroll et al., the disclosures of which documents is incorporated herein by reference. These machines are directed by a human holding the machine to suck air from the surface of inspected luggage. The machines may heat the surface of the luggage and/or direct jets of air at the luggage in order to aid in dislodging vapors from the luggage. These hand held collection apparatus suffer from high cost of operators who need to pass the machine over the luggage and from low accuracy due to collection of only a small portion of the air surrounding the luggage.
Instead of bringing the collection apparatus to the inspected luggage, some systems suggest the use of a swab or brush to remove samples from the luggage. Particles collected by the swab or brush are then provided to the detection system.
Other collection systems include chambers into which the luggage is inserted, such as described in U.S. Pat. Nos. 5,942,699 and 6,324,927 to Ornath et al., U.S. Pat. No. 4,580,440 to Reid et al., U.S. Pat. No. 5,162,652 to Cohen et al., U.S. Pat. No. 3,942,357 to Jenkins et al., U.S. Pat. No. 3,998,101 to Bradshaw et al., the disclosures of which documents is incorporated herein by reference. The luggage is preferably sealed in the chamber and various methods are used to dislodge vapors from the luggage. The air in the chamber is then passed to an inspection system. The volume of air in these chambers is generally too large such that some contaminants having low dilution rates are not detected.
Other collection systems are directed to checking humans and therefore are not sealed. The operation of these systems is similar to that described above, except that there is no airtight seal. Such systems are described, for example, in U.S. Pat. No. 4,909,089 to Achter et al., and U.S. Pat. No. 5,345,809 to Corrigan et al., the disclosures of which documents is incorporated herein by reference.
One of the methods used to dislodge vapors from humans and luggage is air jets directed at the inspected humans or luggage, as described, for example, in U.S. Pat. No. 4,909,089. In some cases it may be desired to avoid directing air jets at humans, especially at their face. U.S. Pat. No. 4,909,089 suggests suppressing air jets directed at the inspected human's face. U.S. Pat. No. 4,987,767 describes a sampling chamber in which air jet streams are injected from a plurality of ducts in different sides of the chamber so as to induce air flow from the floor of the chamber to its ceiling. This air flow sweeps over individuals or objects passing through the chamber. U.S. Pat. No. 6,073,499 to Settles, the disclosure of which is incorporated herein by reference, describes a portal which relies upon the heat of the human body to generate flow of air towards the ceiling of the portal.